Advics Co., Ltd.

Kazuma Kondo

Takashi Watanabe

Masaki Ninoyu

Tetsuaki Tsuzuki

Kentaro Yuasa

A parking brake control device performs a releasing control with good precision by more precisely maintaining clearance between a friction-applying member and a friction-applied member. During a releasing control, a timing at which a braking force generated by an electric parking brakedrops to zero is detected based on a change in a motor current, and a second releasing operation time is set according to the magnitude of the motor current at the time the braking force drops to zero. This makes it possible for the second releasing operation time to be set in accordance with fluctuations in a motor load due to temperature changes or the like. Therefore, a clearance between a brake pad and a brake disc can be kept constant according to the motor load.

Parking brake control device

When a brake force is generated by a service brake in accordance with the depression of a brake pedal by a driver, a brake force generated by an electric parking brake is reduced when lock control is performed, taking the brake force generated by the service brake into consideration. More specifically, a target motor current value increase amount is corrected such that as the brake force generated by the service brake becomes larger, the target motor current value increase amount becomes smaller. Thus, when brake force is generated by the electric parking brake and the service brake compensates for the brake force, it is possible to inhibit generation of a brake force larger than necessary.

Parking brake control unit

A motor current detecting device is provided in a parking brake control system for detecting electric current flowing through an electric motor. And current supply to the electric motor is stopped in case of carrying out a parking brake releasing operation, when a time period in which a differentiated value of the electric current flowing through the electric motor is smaller than a predetermined threshold value exceeds a predetermined time. As a result, a partial braking condition, in which parking brake force partly remains even after the parking brake releasing operation, and which is caused by, for example, the elongation of the brake cable is prevented.

Parking brake control system

The parking brake control device sets a lock control target tension TTAR to a value which depends on the brake fluid pressure (i.e. M/C pressure), wherein the lock control target tension TTAR is used as a threshold determining whether the condition for terminating a lock control is satisfied or not. This operation is aimed for compensating the decrease of the tension applied to the brake cable which occurs caused by the service brake when the service brake is operating and does not occur when the service brake is not operating. Therefore, it is possible to prevent the service brake from causing a problem in which the lock control is terminated while a desired brake force is not achieved at the EPB.

In a parking brake control device, the minimum value of a motor current is set as an idle current after a motor begins to be driven, specifically, in a period during which the idle current is being sampled. As a result, the idle current is set to a value which reflects the temperature of an electric parking brake and the dispersion of individual units of the motor. Accordingly, it is possible to provide a parking brake control device, which can set a target current value capable of coping with the dispersion of the individual units of the motor by calculating the target current value by adding a target effective current necessary to generate an actuation force to the idle current set as described above.

When a release control is executed while a service brake is operating, a parking brake control device continues the release control until a first predetermined time passes even if the pressing force for moving a friction material becomes a target value, wherein the first predetermined time is a time period which is longer than a time period which it is supposed to take until the negative influence of the service brake vanishes.

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Aichi-gun, Japan

Kazuma Kondo